The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Conventional thread taps use high volume flow of a liquid lubricant over the cutting edges of the tool. Some thread taps have an internal passage that provide this liquid lubricant to each cutting edge. Since the liquid lubricant is essentially an incompressible fluid, flow from the passage to each cutting edge remains substantially based on the pressure of the liquid supplied to the tool.
In contrast, minimum quantity lubrication (“MQL”) machining uses lubrication supplied to the cutting edges of a tool through a lean air-oil mist, rather than through the high volume liquid-based emulsion in conventional thread tapping. The ratio of air to oil in the air-oil mist is typically very high and the lubricant mist acts as a compressible fluid (unlike the incompressible liquid lubricant of conventional thread tapping). Taps designed for liquid lubricant flow through internal passages suffer from excessive air compression and backpressure when used with the air-oil mist of MQL machining. This can result in wasted lubricant and excess wear on the tap.
The present disclosure provides a thread tap having a more balanced lubrication flow for MQL thread tapping that overcomes the problems of typical thread taps when used for MQL tapping.